Tamper-resistant fastener and method and tool for use with same

ABSTRACT

A fastener includes a round, blind hole or pocket in its head. Installation and removal of the fastener is accomplished with a tool containing an eccentric segment on the end of a shaft. When rotated within the pocket, the eccentric segment displaces laterally relative to the shaft to provide a friction grip to the lateral wall of the pocket. The strength of the grip is proportional to the applied torque. Eccentric displacement allows rotation but prevents the tool from spinning out of the fastener thereby eliminating cam-out and surface damage resulting from contact with a spinning tool tip. The eccentric head of the tool can be made disposable and to shear off when a predetermined torque is reached. The smooth-sided round hole offers no purchase for commonly available tools; making the fastener tamper-resistance. In another embodiment, the fastener includes a raised portion in the pocket. A tool having a complementary opening shears off the raised portion at a predetermined torque.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/451,383, filed Jun. 13, 2006, now abandoned, which is a divisional ofU.S. patent application Ser. No. 10/970,274, filed Oct. 22, 2004 (nowU.S. Pat. No. 7,066,062), which claims priority to U.S. ProvisionalAppl. No. 60/513,739, filed Oct. 24, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of fasteners and, moreparticularly, to tamper-resistant fasteners (e.g., bolts) and tofasteners requiring tightening to a precise torque.

2. Related Art

In many instances it is necessary to prevent unauthorized intrusion ordisassembly of a product in order to prevent theft or injury. Use ofsuch fasteners on medical equipment ensures that unskilled individualswill not attempt adjustments. Use on cable set-top boxes preventstampering with the electronics within. Use on public structures such asplayground equipment, picnic benches, and on restroom fixtures preventstheft and disassembly-type vandalism.

While it is impossible to stop a determined thief, most applications oftamper-resistant technology require only that access be made verydifficult unless a special tool is used. To accomplish this, priordesigns modified the heads of commonly used bolts and screws to disallowremoval using ordinary wrenches and screwdrivers. Once modified, thehead of the fastener will only mate with a tool that incorporates theanalog of the modified head. It is apparent that this method of creatinga tamper-resistant fastener relies on the relative scarcity ofinstallation tools.

Modifying the head of a fastener to incorporate offset holes, cam-likepockets or steps proves difficult to manufacture due to the hightolerances that must be held. As a result, the price of tamper-resistantfasteners is high. By necessity, the installation tools are encumberedwith a complex, and often quite sharp or dangerous, tool tip. Thisbecomes a hazard during installation when torque is applied and the tooltip cams out of the fastener head and skids across the articles beingjoined. This situation is highly undesirable, dangerous and happens fartoo often using existing designs. Cam-out is a major problem formanufacturers that focus on product quality such as the auto industry.

A further problem with standard and tamper-resistant fasteners relatesto the inability to accurately torque down the fastener during install.Installation torque is dependent upon many factors and is often criticalto holding an assembly together as designed. The most common method forapplying a set amount of torque is to use a tool that incorporates aclutch that releases when a set rotational force is exceeded. Oftenthese tools use a spring as the torque reference for the clutch.Stretching or compression of the spring over time introducesinaccuracies to the torque measurement. Electronic and manualinstallation tools utilize the same general principle and suffer thesame inaccuracies. Electronic systems are generally used in theautomotive and aircraft industries on, for example, door latches andcomponents that may affect the safety of users/passengers.

What is needed is a better fastener and fastening system and method.Moreover, it would be extremely valuable for a fastener to incorporate asingle use torque setting feature into its design. Installation toolmaintenance and calibration would no longer be an issue if the fastenerincluded a feature that would not allow over torqueing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of a representative fastener headillustrating a cylindrical straight-walled pocket in accordance with anembodiment of this invention.

FIG. 2 is an end view of the installation tool illustrating theeccentric relationship between the tool shaft, rotation pin and the tooltip.

FIG. 3 is an orthometric view of an installation tool that may used toturn the fastener of an embodiment of this invention and shows therelationships between components illustrated in FIG. 2.

FIG. 4 is a cross-sectional view of one type of installation tool thatmay be used to turn the fastener of an embodiment of this invention anda representative fastener.

FIG. 5 is an exploded view of the parts necessary to make theinstallation tool of FIG. 4.

FIG. 6 is a cross-sectional view of another version of an installationtool with a rotation pin integral to the tool shank and a representativefastener.

FIG. 7 is an exploded view of the parts necessary to make theinstallation tool of FIG. 6.

FIG. 8 is a cross-sectional view of a representative fastener andanother version of an installation tool that illustrates the use of arotation pin integral to the tool tip that is designed to shear off whena pre-determined installation torque is applied.

FIG. 9 is an exploded view of the parts necessary to make theinstallation tool of FIG. 8.

FIG. 10 is a cross-sectional view of a representative fastener with ahex pocket and a hex or ‘Allen’ wrench tool in accordance with anembodiment of the invention that illustrates use of a rotation pinintegral to the tool shank.

FIG. 11 is an exploded view of the parts necessary to make theinstallation tool of FIG. 10 and top view of a typical hex headedfastener.

FIG. 12 is a top view of the hex fastener of FIG. 10.

FIG. 13 is an orthometric view of the shaft, tip, rotation pin andhandle that would comprise a hand installation tool in accordance withthe present invention.

FIG. 14 is a cross-sectional view of a fastener designed to accept amolded rubber or thermoplastic rubber cap that serves as both a foot anda means of concealing the cylindrical pocket.

FIG. 15 is a cross-sectional view of another embodiment of a fasteneraccording to the invention.

FIG. 16 is a top view of the head of the fastener of FIG. 15.

FIG. 17 is a tool for installing the fastener of FIG. 15.

FIG. 18 is a cross-sectional view of the fastener of FIG. 15 aligned formating with the tool of FIG. 17.

FIG. 19 is a cross-sectional view of another embodiment of a fasteneraccording to the invention.

FIG. 20 is an installation tool which uses a vacuum to remove a shearpin after it is sheared from a fastener.

FIG. 21 is a cross-sectional view of the fastener of FIG. 19 aligned formating with the tool of FIG. 20.

FIG. 22 is a cross-sectional view of another embodiment of a fasteneraccording to the invention.

FIG. 23 is a top view of the head of the fastener of FIG. 22.

FIG. 24 is a cross-sectional view of another embodiment of a fasteneraccording to the invention.

FIG. 25 is a top view of the head of the fastener of FIG. 24.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with an embodiment of the present invention, a fastenerincorporates a smooth-sided pocket (or bore) in the fastener head oncenterline with the threads that can be made using a standard drill bit.A feature of this embodiment is a tamper-resistant fastener headgeometry that may be adapted to various fasteners. The tamper-resistantfastener cannot be operated with conventional tools. A further featureof this embodiment is a fastener head geometry and installation toolthat allows high installation torque with correspondingly high axialfriction thereby preventing cam-out. The installation tool is easy toconstruct and can be adapted for either manual or automated use.

Another embodiment of the invention provides a fastener that can beprecisely torqued to a desired value by virtue of a shear pin either onthe installation tool or on the fastener itself.

A feature of an embodiment of this invention is a tamper-resistantfastener that can be used more than once, if desired.

Yet another feature of an embodiment of the present invention is amethod of engaging the fastener so a disposable part of the installationtool tip or a disposable part of the fastener snaps off when apredetermined torque is reached thereby ensuring proper installationtorque.

Yet a further feature of an embodiment the present invention is that thepocket in the headed-end (i.e., head) of the fastener is filled with aresilient material after installation thereby discouraging attempts toremove the fastener. The resilient material can also act as avibration-reducing stand-off, bumper, or non-skid foot.

Still another feature of an embodiment of the invention is a tool thatcan be used with the fastener of the invention, with hex (Allen) headbolts, and/or with stripped hex bolts. Moreover, the tool of theinvention can be used to remove broken bolts, studs and/or shanks fromthreaded holes.

Other features and advantages of this invention are described below orwill be apparent to those skilled in the art based on the disclosure setforth herein.

FIG. 1 illustrates a representative construction of a tamper-resistantfastener 2 according to an embodiment of the invention. The outersidewall 6 of the fastener head is preferably chamfered or radiused tomake it difficult to apply torque to the fastener with any standardtool. The head of the fastener is attached to a conventional threadedshank, which may be installed as would a normal screw or bolt. Thepocket 4 in the fastener head 2 has cylindrical, straight andsubstantially parallel sidewalls 4 of a type that would be createdthrough the use of a standard metal drill bit. The one hundred andeighteen degree (118°) included angle at the bottom of the pocket 8 isnot critical but chosen to match the one hundred and eighteen degree(118°) cutting end geometry of commonly available twist drills of thetype used on high speed equipment.

In the fastener embodiment described by FIG. 1, the head of the fasteneris preferably made of hardened steel to resist attempts to tap, cut intoor form a means of engagement for a conventional screwdriver or otherremoval tool.

FIG. 2 illustrates the end view of one embodiment of an installationtool needed to rotate the fastener shown in FIG. 1 and the relationshipsnecessary to enable the tool tip 10 (also called a bit), rotation pin 12and the tool shank 28 (also called a shaft) to act in concert to applyrotational force to fastener pocket 4. Rotation pin 12 is insertedthrough the tool tip 10 and into the tool shank 28. The rotation pin 12allows the tool tip 10 to rotate freely about it but is fixed within thetool shank 28 by a frictional or press fit, retaining adhesive such asLoctite 680 from the Loctite Corporation, a setscrew or any other mannerof attachment. The tool tip 10 and tool shank 28 are sized to create afree fit within the pocket 4 of the fastener 2, when both the tool tip10 and tool shank 28 are concentric and axially aligned to create acylinder. When this condition is met, the installation tool composed ofthe tool tip 10, the rotation pin 12 and the tool shank 28 may beinserted or withdrawn from the pocket 4 of fastener 2 withoutdifficulty, because the installation tool diameter 20 is smaller thanthe fastener pocket diameter 22.

Rotation pin 12 is inserted axially through the tool tip 10 into thetool shank 28 on an axis 16 that is offset a small distance 18 from thecentral axis 14 of shank 28 and tip 10. In this configuration, when thetool tip 10 is rotated one hundred and eighty degrees (180°) relative tothe tool shank 28, the effective diameter of the tool tip 10 and toolshank 28 will be increased by two times the offset 18. The increase indiameter will cause the tool tip 10 to axially contact the fastener 2pocket surface 4 at position 24, while the tool shank axially contactsthe pocket surface 4 at position 26; thereby imparting a largetangential force component due to the relative eccentric motion of theinstallation tool components. The tangential force exerted by theinstallation tool components against the fastener 2 pocket sidewalls 4is proportional to the torque applied to the tool shank 28 by eithermanual or mechanical means. By nature of the design, tangential force isonly applied to the fastener 2 pocket sidewalls 4 at positions 24 and 26when torque is applied to the tool shank 28, thus substantiallyeliminating the tendency of the driving tool to pull out or cam out ofthe fastener.

In a preferred embodiment, for example, the single axis offset 18 willbe at least twenty percent (20%) greater than the difference betweendiameter 20 (of the tool tip 10 and tool shank 28 when concentricallyaligned) and diameter 22 (of the pocket 4 of fastener 2).

When the tool tip 10 of the installation tool shown in FIG. 3 isinserted into the pocket 4, and pressed against the bottom surface 8 ofthe pocket 4 of fastener 2, it will resist rotation relative to the toolshank 28 and cause the tool shank 28 to rotate relative to the tool tip10 and thus frictionally engage the sidewall of pocket sidewall.

FIG. 3 is an orthometric view of a special drive tool needed to applytorque to the tamper-resistant fastener of FIG. 1, with the tool tip 10one hundred and eighty degrees (180°) out of alignment with the toolshank 28. It should be noted that the maximum torque that can be appliedto the shank 28 and tip 10 combination is limited by the shear strengthof the rotation pin 12.

FIGS. 4 and 5 show installation tip geometry as illustrated in FIG. 2and FIG. 3. In this embodiment of the installation tool, the tool tip 32is referenced and held to the end of the tool shank 28 by a rotation pin36 that mates with a receiving hole 30 in the tool shank 28 through thetool tip. The rotation pin has a flattened head 38 that will not allowthe tool tip 32 to slip off the rotation pin 36. This keeps the tool tip32 in offset axial alignment 18 with the tool shank 28 while stillallowing it to rotate freely relative to the tool shank 28.

FIGS. 6 and 7 show installation tip geometry as illustrated in FIG. 2and FIG. 3.

In this embodiment of the installation tool, however, the tool tip 44 isreferenced and held to the end of the tool shank 40 by a rotation pin 42that is turned or machined into the tip of the tool shank 40. Therotation pin 42 mates with the tool tip 44 through a hole in the tooltip 44 allowing free rotation of the tool tip 44 about the rotation pin42 which is part of the tool shank 40. A clip 48 (e.g., a “C” clip) canbe installed over the rotation pin 42 in such a manner that the tool tip44 is captured to the tool shank 40 by the clip 48. It should beunderstood that there are many other ways to secure the tool tip 44 tothe rotation pin 42 so that it does not fall off. For example, therotation pin 42 and/or the tool tip 44 can be magnetized such thatmagnetic force holds the tool tip on the rotation pin. Alternatively,the end of the rotation pin 42 can be coined, peened or swaged toincrease its diameter at its distal end which extends through a portionof the tool tip. Other securing means and methods will be apparent tothose skilled in the relevant art.

FIGS. 8 and 9 show installation tip geometry as illustrated in FIG. 2and FIG. 3. In this further embodiment of the installation tool, thedisposable, single use, tool tip 56 is referenced to the end of toolshank 50 by a rotation pin 54 that is turned, machined, pressed, weldedor adhered to the tool tip 56. The rotation pin 54 freely mates with ahole or bore 52 of shank 50 allowing rotation of the tool tip 56 aboutrotation pin 54. The base 60 of the rotation pin 54 is scored orsubstantially relieved in a manner calculated to place the rotation pin54 under great shear force when the tool tip 56 and tool shank 50 arerotated in an eccentric manner relative to each other as illustrated byFIG. 2. At the pre-calculated torque, rotation pin 54 will shear off atthe relieved portion 60 of the pin, and the tool shank 50 will freelyrotate within the pocket 4 of fastener 2, thus preventing furthertightening of the fastener 2. It should be understood that there aremany ways to modify the tool tip 56 and rotation pin 54 such that thetool tip 56 may be retained in the fastener 2 or withdrawn by theinstallation tool for disposal.

After shear-off, pin 54 will fall out of bore 52 thereby clearing bore52 for use of tool shank 50 with another tool tip 56 and pin 54.Alternatively, in an alternate embodiment of the tool of FIGS. 8 and 9,bore 52 can be extended through shank 50. A spring-loaded rod or plunger(not shown) could then be positioned within bore 52 for ejecting thesheared pin from the distal end of the bore.

Means may also be added to tool shank 50 to retain pin 54 until it ismanually removed. Such means may include, for example, a reduceddiameter or necked down portion of bore 52 to add additional friction toretain the pin 54 in the bore 52. A thin disk of compliant material(e.g., silicone, rubber or the like) covering the end of shank 50 canalso be used. A reduced diameter hole in the disk could allow passage ofpin 54 through the disk and into bore 52 and would provide friction tohold pin 54 in place. A spring actuated retaining ring or ball bearingcould also be used within bore 52 to apply a frictional force to pin 54and optionally mate with a groove or indentation on pin 54. Other meansfor holding pin in bore 52 will be apparent to a person skilled in therelevant art.

FIGS. 10 and 11 show installation tip geometry as illustrated in FIG. 2and FIG. 3 but specifically adapted to a hex-headed fastener 70 which isconventionally installed using a hex shaped tool often called an ‘Allen’wrench. FIG. 12 is a top viewing illustrating the hexagonal pocket 72formed in the top of hex bolt 70. In this embodiment of the installationtool 64, the tool tip 68 is referenced and held to the end of the toolshank 64 by a rotation pin 66 that mates with a receiving hole in thetool tip 68. The rotation pin 66 and attachment method may besubstantially similar to any of those described above with reference toFIGS. 4-5, 6-7 or 8-9. The separate rotation pin 36 or integral rotationpin 66 may have a flattened head 38 that will not allow the tool tip 68to slip off the rotation pin 66, thus keeping the tool tip 68 in offsetaxial alignment 18 with the tool shank 64 but allowing it to rotatefreely relative to the tool shank 64.

Damage to the walls of the hex pocket 72 in the head of a cap head orbutton head bolt 70 often causes the pocket to become substantiallyrounded, hindering or preventing engagement by the hex perimeter of astandard hex or Allen tool. The invention solves this problem. Asillustrated in FIGS. 10 and 11, the shank 64 and tool tip 68 are formedin a hexagonal shape to mate with the hexagonal pocket 72 of the hexbolt 70. This brings the advantages of an embodiment of the invention asdescribed above to a hex fastener. In so doing, the shank 64 and tooltip 68 will tightly engage with hex pocket 72 and prevent cam-out orstripping of pocket 72. Furthermore, the tool can be used to remove hexbolts that have been stripped by a conventional tool. The novellocking/gripping feature of this embodiment of the invention willtightly couple to the lateral walls of a stripped hex pocket.

While not as ideal, the offset rotational driving geometry described inFIG. 2 will also allow a round tipped installation tool as illustratedin FIGS. 4-9 to install or remove a fastener with a hex pocket if thetool shank and tool tip are slightly smaller in diameter than theinscribed perimeter of the fastener pocket 72.

FIG. 13 illustrates a hand installation tool with an integral hand grip74 connecting axially to a tool shank 28 (or any of the other toolshanks discussed above) and tool tip 10 (or any of the other tool tipsdiscussed above) of construction described herein. For use in apneumatic or electrically actuated tool, the tool shank may incorporateflats or ridges at the driving end or be machined to fit into a standarddrill chuck or hex bit adaptor.

FIG. 14 shows an embodiment of a tamper-resistant fastener 76 accordingto an embodiment of the invention. Fastener 76 has a slopedcircumferential or radial surface 81 about its head. Like the radiusedhead of fastener 2 (see FIG. 1), the sloped surface 81 makes itdifficult for a tool such as pliers to get a grip on the head offastener 76. This enhances the tamper-resistance of fastener 76 bymaking it difficult to remove with standard tools.

FIG. 14 also illustrates how the pocket 4 of fastener 76 can furtherserve as a receptacle for a projection 80 of an elastomer anti-skid foot78. Foot 78 can be made from rubber, an injection moldable thermoplasticsuch as Dupont ENGAGE®, or any other resilient material so that thebottom surface 82 prevents scratching or unwanted movement. On productssuch as a TV set-top box, the fastener 76 of this embodiment can be usedto hold the unit together. Once installed, molded foot caps 78 can bepressed into pocket 4 of fastener 76 and held in place by projection 80;thus providing a foot that is resistant to side loads and camouflagesthe nature of the underlying tamper-resistant fastener. The foot 78 canalso act as a resilient bumper or vibration-isolating standoff.

Thus, as described above, a tool constructed in accordance withembodiments of the invention can be used with a bolt having acylindrical (i.e., circular) pocket or bore. A tool according to theinvention can also be used with fasteners having other shapes such ashexagon-shaped (e.g., an Allen head bolt). Furthermore, the tool can beused to remove (or install) bolts which have pockets that have beenstripped (i.e., a slipping tool, such as a conventional Allen wrench,has turned within the pocket and has rounded-off the corners of thehexagon-shaped pocket). Because the tool does not require edges todevelop grip or purchase, the tool will effectively remove strippedbolts.

Furthermore, the tool can be used to extract a broken bolt, shank orstud. Conventionally, a broken shank is removed by drilling a hole in itand inserting a tool known as an easy-out, EZ-out, or stud extractor.When the easy-out is rotated within the hole, edges of the easy-out aresupposed to “bite” into the lateral walls of the hole and transfertorque from the easy-out to the broken shank. Unfortunately, theeasy-out often is unable to get sufficient bite to transfer sufficienttorque to remove the broken shank. Furthermore, the easy-outs aretypically made from very hard, brittle material and are easilybroken-off in the shank.

In contrast, the eccentric, cam-like action of the tool grips a brokenshank without requiring the hardening that makes the easy-outs so easilybroken. In operation, the tool can be inserted into a hole drilled intoa broken shank. Torque can then be applied to the shaft of the tool toremove the shank. The tool effectively transfers the torque from theshaft to the broken shank without slippage.

Additional embodiments of the invention are shown in FIGS. 15-25. Theseembodiments are particularly useful for applying a precise tighteningtorque to a fastener.

FIG. 15 is a sectional view of a fastener 150. Fastener 150 is similarto the fasteners described above, having a round or cylindrical pocketformed in the head thereof. However, fastener 150 includes a pin 88integrally formed (e.g., by molding, forging or machining) in the pocket85. Pin 88 is configured to shear off at a point 89 at a predeterminedtorque. By controlling the composition and diameter of pin 89, thepredetermined torque can be tightly controlled and predicted.

FIG. 16 is a top view of the fastener of FIG. 15, illustrating pin 91 inpocket 85. Note that pin 88 is offset from a center axis of fastener 2.This is illustrated in FIG. 15 by an offset between axes 86 and 87,where axis 86 is the central axis of fastener 150, and axis 87 is thecentral axis of pin 88.

Fastener 150 can be installed using a tool 172 as shown in FIG. 17. Tool172 includes a handle 74 and a shank 93. An axial bore or hole 92 formedin the distal end of shank 93 is adapted to receive pin 88. As discussedin detail above for alternate embodiments of the invention, bore 92 isoffset from the center axis of the shank 93. Unlike the previouslydescribed embodiments, however, there is no separate tool tip attachedto tool 172.

As shown in FIG. 18, the circumferential surface 174 of the distal endof tool shank 93 is adapted to mate with the inner walls of pocket 85 offastener 150. The axial offset of bore 92 is matched to the axial offsetof pin 88. Thus, when the properly aligned, the distal tip of shank 93can be inserted into pocket 85 and pin 88 is inserted into bore 92.Thereafter, rotation of shank 93 relative to fastener 150 will cause thecircumferential surface 174 of shank 93 to engage the inner wall ofpocket 85 such that torque on shank 93 can then be imparted to fastener150.

If the applied torque exceeds the shear strength of pin 88, then pin 88will shear off, preventing additional torque from being applied tofastener 150. As discussed above, pin 88 is configured to shear off inthis manner, and the composition and diameter of the pin can be chosento precisely control the maximum torque that can be applied to thefastener.

An alternate embodiment 190 of fastener 150 is shown in FIG. 19.Fastener 190 is similar to fastener 150, except that pin 88 has beenreplaced with a pin-receiving hole or bore 192 formed in the body of thefastener in the place of pin 88. Bore 192 is configured to receive a pin102. Pin 102 may be secured in bore 192 by a friction or press fit, anadhesive, welding, soldering or some other means. Like pin 88, pin 102is configured to shear off at a point 103.

An advantage of fastener 190 as compared to fastener 150 is that adifferent material can be used to form pin 102. For example, pin 102 canbe very precisely formed from metal or sintered metal (e.g., byextrusion, turning, casting or the like) or from a plastic (e.g., byextrusion, injection molding or the like) or from another suitablematerial. Manufacture of fastener 190 may be more complicated, becausean additional step is required to insert the pin in bore 192. However,the additional complexity may be justified for many applications.

Fastener 190 can be installed using a tool 172 as shown in FIG. 17.Alternatively, a tool 202 can be used for either fastener 150 or 190.Tool 202, shown in FIGS. 20 and 21, is similar to tool 172. However, theaxial bore or hole 92 in shank 93 is connected to a vacuum source 108.As illustrated, bore 92 is coupled to a larger diameter bore 110 thatpasses through shank 93 to deliver a vacuum to the distal tip of shank93. Upon shearing of pin 102, the vacuum will pull pin 102 through shank93 and into a waste/recycle receptacle (not shown) associated with thevacuum source.

In another embodiment of the invention, the surface of the bit and/orthe surface of the end of the tool shaft adjacent the tip can beroughened to enhance the bite, grip or purchase that the tool will makewhen inserted into a smooth pocket or bore. For example, these surfacescan be serrated. Alternatively, carbide or diamond particles can beembedded in the surfaces.

In another embodiment, an end cap (e.g., made from a plastic or rubberbased material) can be attached to the distal end of the bit. Forexample, referring to FIG. 7, a plastic end cap could be attached to thedistal end of bit/tip 44. This end cap will help prevent the tool fromscratching surfaces adjacent a bolt in the event that a user misalignsthe tool with the bolt head when attempting to use the tool. Thisfeature would be especially advantageous to working environments likeautomobile manufacturing plants where scratch damage is a major concern.

As will be apparent to a person skilled in the art after reviewing theembodiments of FIGS. 15, 16, 18, 19 and 21, advantages of embodiments ofthe invention may also be obtained in a fastener that does not use theeccentric concept. For example, FIG. 22 is a sectional view showing afastener 222 having a pocket 85 in which two pins 224 are formed (orplaced, e.g., by pressing into corresponding holes). FIG. 23 is a topview of fastener 222. Note that a corresponding tool shank (e.g.,similar to that of FIG. 17) would have bores corresponding to pins 224.The pins could be used to drive fastener 222 to a desired torque atwhich point pins 224 would shear off.

As another example, FIG. 24 is a sectional view showing a fastener 242having a pocket 85 in which a raised portion 244 is formed (or mounted).FIG. 25 is a top view of fastener 242. Note that the plus sign shape ofraised portion 244 will provide a tool with purchase or grip to transfertorque to fastener 242. Note also that a corresponding tool shank (e.g.,similar to that of FIG. 17) would have a bore having a shapecomplementary to raised portion 244. Raised portion 244 would allow thefastener to be drive to a desired torque at which point raised portion244 would shear off.

Based on these examples, it will be apparent to a person skilled in theart that other configurations and shapes of raised portions can be usedin the pocket of a fastener to drive the fastener and to then shear offat a desired torque. Such other configurations and shapes are within thescope of this embodiment of the invention. The term “raised portion” asused herein is intended to include pins or other elements raised fromthe bottom face or floor of a pocket formed in a fastener head.

In the various embodiments of the invention discussed herein, atamper-resistant fastener has been described. It should be understood,however, that non tamper-resistant fasteners may also benefit fromadvantages of the invention. For example, the invention's ability todrive a fastener to a desired torque can be used with nontamper-resistant fasteners such as an ordinary hex head bolt. A pocketas described herein could be formed in the head of the bolt. The tooltip of FIGS. 8 and 9 could then be used to install the bolt with aprecise torque. If removal of the bolt later becomes necessary, a wrenchmating with the hex-shape on the outer surface of the bolt head can beused to remove the bolt.

Similarly, the pocket/pin/raised portion combinations of FIGS. 15, 16,18, 19, and 21-25 can be implemented in an ordinary hex head bolt. Theappropriate tool (e.g., one of the tools of FIG. 17 or 20) could then beused to install the bolt. If removal of the bolt later becomesnecessary, the hex-shape on the outer surface of the bolt head can beused to remove the bolt.

Finally, the tools of the various embodiments of the invention can bemade in a variety of different sizes for use with a variety of differentsize bolts. The tools can also be made form a variety of materialsincluding steel, hardened steel, titanium, aluminum, and the like.

The fasteners of the various embodiments of the invention can also bemade from a variety of materials including steel, hardened steel,titanium, aluminum, ceramic, various plastics and the like.

Advantages of the present invention have been fulfilled by the variousinstallation tools, methods and fastener head designs disclosed herein.It should be noted that further modifications of the invention arepossible and will be apparent to those skilled in the art based on thisdisclosure. Thus, the scope of the present invention should not belimited to the specific embodiments set forth herein, but is defined bythe claims appended hereto.

1. A kit comprising: a fastener having a threaded shank defining alongitudinal axis and a head attached to the threaded shank along thelongitudinal axis, the head having a pocket formed therein, the pocketconsisting essentially of a cylindrical bore coincident with thelongitudinal axis; and a tool for use with the fastener, the toolincluding a tool shank defining a second longitudinal axis, and a bitrotatably coupled to an end of the tool shank, the bit rotatable about athird axis independent of rotation of the tool shank, wherein the thirdaxis is substantially parallel to and offset from the secondlongitudinal axis, wherein the end of the tool shank including the bitis configured for insertion into the pocket of the fastener when the bitis aligned with the end of the tool shank and is configured to gripsides of the pocket upon application of a rotational force to the toolshank.
 2. The kit of claim 1, wherein the tool shank has a substantiallycylindrical shape at the end, the bit has a substantially cylindricalshape, and the end of the tool shank and the bit have approximately thesame diameters.
 3. The kit of claim 2, wherein the removal tool furthercomprises: a handle attached to a second end of the tool shank.
 4. Thekit of claim 2, wherein the bit is coupled to the tool shank by a pin.